The candidate is a recently promoted Research Assistant Professor who has been investigating the use of dendritic cells to activate CD8+ T cell responses against melanoma in the laboratory of Dr. V. Engelhard. As part of a move towards independence, the candidate is developing his own research project that extrapolates from his postdoctoral investigations. It is the candidate's intention to use the Temin Award as a foundation to advance intellectually and scientifically under the mentorship provided by Dr. Engelhard, followed by a successful transition to completely independent research in tumor immunotherapy. The University of Virginia provides an ideal environment for this proposal due to the excellence of the basic science faculty and the potential for collaboration with physicians interested in applying immunotherapy in a clinical setting. The research proposal is based on the accumulated data from several groups that suggests that CD4+ T cells play an integral role in directing adaptive immune responses against tumors, by providing activation stimuli for professional antigen presenting cells, cytokine support the generation of effector and memory CD8+ T cells and direct anti-tumoricidal activity. Therefore, vaccination protocols that elicit CD8+ T cell and CD4+ T cell responses against tumors are likely to be more effective than those that target either arm of the adaptive immune response alone. Based on the hypothesis that the generation of CD4+ T cells that can respond specifically to MHC class II-restricted epitopes derived from melanocyte differentiation proteins will enhance the generation of tumor-specific CD8+ T cell responses, and the generation of memory CD8+ T cells against melanoma, we propose to: 1. Identify and compare HLA-DR*0401- restricted peptides derived from tyrosinase that are presented on dendritic cells, melanoma cells, or both. 2. Characterize the CD4+ T cell response to tyrosinase-derived HLA-DR*0401-restricted peptides in DR4/IEd transgenic mice that either do or do not express tyrosinase in the periphery. 3. Define the role of tyrosinase-specific CD4+ T cells and their epitopes in the generation of tyrosinase-specific CD8+ T cells and anti-melanoma responses. The results derived from this proposal are expected to have immediate impact on our understanding of the immune response to peripherally expressed self-antigens t h a t are relevant to melanoma, and the design of immunotherapeutic interventions against melanoma.